When asked why the company did not immediately alert the 87 million users whose data may have been improperly accessed when first told about it in 2015, Zuckerberg said Facebook considered it a "closed case" after Cambridge Analytica said they had deleted it.
Facing his second day of questioning from members of Congress on Wednesday, Zuckerberg was answering a question from Rep. Anna Eshoo, a Democrat from California. These allegations have taken an aggressive turn and have cause concern over whether this data was then used to try to sway the outcome of the 2016 US presidential election and the Brexit vote.
Because after watching lawmakers fumble their way through the questions they posed to Zuckerberg, who'd swapped his customary hoodie for what appeared to be his dad's suit, it's not clear the majority of them possess the baseline understanding of what Facebook does to responsibly regulate it.
Zuckerberg said that Facebook allows people to decide whether and how they want their information shared. "It was built to accomplish a social mission - to make the world more open and connected", Mark Zuckerberg wrote in Facebook's S-1 filing.
39% said they were "very aware" of the Cambridge Analytica scandal, while 37% said they were "somewhat aware".
The following day, he was asked by Congressman Ben Lujan about the data collected on people who had never even signed up to Facebook.
Nine per cent of Americans in a new survey said they had deleted their Facebook account over privacy concerns. A Facebook statement last week promised to tighten control over those apps and their use of data. In some instances, they anxious that Facebook wasn't taking down harmful content fast enough, like fake profiles of people who are stealing pictures from real people, as well as posts seeking to recruit for terrorist ideologies.
In his opening remarks at US Congress, he said: "Facebook is an idealistic and optimistic company".
He told me that Dr Kogan's work had raised issues for the university: "Even if an academic does something - quote unquote in their "spare time", with their own company - they still ought to be held to professional standards as a psychologist". But he said his company "can do a better job of explaining how advertising works".
Earlier this year, Mueller charged 13 Russian individuals and three Russian companies in a plot to interfere in the 2016 presidential election through a social media propaganda effort that included online ad purchases using U.S. aliases and politicking on USA soil. "I could have set up an identity watch and bank watch to see if any activity was flagged for being unusual", she said. "Right there. Not buried in the settings somewhere but right there", Zuckerberg said. "In this period of time, right now in social networking they are a monopoly, but that monopoly will not persist forever", Hoffman said.
Curious to see what Facebook itself knows about you?
But in the wake of the Cambridge Analytica scandal and this week's hearings, lawmakers and the public are growing more concerned about Facebook's data collection practices.
Sen. Lindsey Graham, R-S.C., pressed Zuckerberg on Facebook's market power. There isn't a place on the internet Facebook doesn't touch with the many companies it has acquired.